Trabecular myocytes of the embryonic heart require N-cadherin for migratory unit identity.
The myocardial wall of the vertebrate heart changes from a simple epithelium to a trabeculated structure during embryogenesis. This process occurs when epithelioid cardiomyocytes migrate toward the endocardium, which we show is coincident with up-regulation of the cell adhesion molecule, N-cadherin. To study the role of N-cadherin expressed at the trabeculation stage, a replication-defective retrovirus expressing a dominant negative mutant of N-cadherin (delta N-cadherin) was engineered. Control viruses were designed to express beta-galactosidase or a full-length N-cadherin. Viruses were introduced into epithelioid presumptive myocytes at the time they initiate the epithelial-mesenchymal transformation. Individual cells infected with control viruses generated daughter myocytes which migrated toward endocardium as a tight cluster, thereby generating a clone that forms a single or at most two trabeculae. In contrast, myocytes expressing delta N-cadherin were sparsely distributed within the myocardium and failed to form the ridge-shaped clone. Thus, in addition to its known roles in myocyte epithelialization and intercalated disc formation, N-cadherin appears to play a role in homotypic interactions between nonepithelial migratory myocytes during trabecular formation of the embryonic heart.
Ong
L L
LL
Department of Cell Biology and Anatomy, Cornell University Medical College, New York, New York 10021, USA.
Kim
N
N
Mima
T
T
Cohen-Gould
L
L
Mikawa
T
T
D000818:Animals; D015820:Cadherins / Q000032:analysis / Q000502:physiology*; D002448:Cell Adhesion; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology*; D002642:Chick Embryo; D018920:Coculture Techniques; D004285:Dogs; D004699:Endocardium / Q000166:cytology / Q000196:embryology; D004847:Epithelial Cells; D005822:Genetic Vectors / Q000235:genetics; D006321:Heart / Q000196:embryology*; D008648:Mesoderm; D009206:Myocardium / Q000737:chemistry / Q000166:cytology* / Q000648:ultrastructure; D012190:Retroviridae / Q000235:genetics; D017384:Sequence Deletion
D015820:Cadherins